1. Field of the Invention
The present invention relates to a liquid crystal display and a driving method to be used for the liquid crystal display and more particularly to the liquid crystal display that can be suitably used when an image including a moving image part and a static image part in a mixed manner is to be displayed and the method for driving the liquid crystal display.
The present application claims priority of Japanese Patent Application No. 2003-332283 filed on Sep. 24, 2003, which is hereby incorporated by reference.
2. Description of the Related Art
In recent years, a liquid crystal display, in particular, out of image display devices, has become large in size and high definition and is used not only for a device to display a static image such as images in a personal computer, word processor, or a like but also for a device to display a moving image such as images in a TV (television) or a like. It is anticipated that a penetration rate of a liquid crystal display in general homes, since its depth is shorter and its occupying area is smaller when compared with those in a TV having a CRT (Cathode Ray Tube), becomes high.
In the case of a liquid crystal display, since image data (pixel data) that appeared one frame before is left until new image data is written, an image retention phenomenon or a blur of an edge occurs when a moving image is to be displayed. To solve the problem with the phenomenon, a method in which a backlight is driven by an impulse is available, however, due to the driving method using the impulse, a flicker occurs on a display screen. The flicker is inconspicuous while a moving image is being displayed but becomes conspicuous while a static image is being displayed in some cases and, therefore, a liquid crystal display capable of suppressing the occurrence of a flicker is proposed.
Such the conventional technology is disclosed in, for example, Japanese Patent Application Laid-open No. 2001-296841 (Pages 11 and 14, and FIGS. 3 and 11.) FIG. 6 is a schematic diagram illustrating configurations of a conventional liquid crystal display disclosed in the above patent reference. The liquid crystal display, as shown in FIG. 6, is made up of a switching section 1, a high-speed switch 2, lamps 3a and 3b, a light guide section 4, and a liquid crystal panel 5. In the liquid crystal display device, whether an image to be displayed is a moving image or a static image is judged by a judging section (not shown) and, when the image to be displayed is a moving image, power is fed through the switching section 1 to the high-speed switch 2 and the lamps 3a and 3b operating as a backlight flash alternately during one frame of a video inputting signal. Then, light from the lamps 3a and 3b is diffused by the light guide section 4 to a direction of the liquid crystal panel 5 and is modulated in a manner to correspond to a display image on the liquid crystal panel 5 and is then emitted to a side of a display surface (screen). Moreover, when the image to be displayed is a static image, power is fed through the switching section 1 to the lamp 3a to allow the lamp 3a to be turned ON all the time. The light from the lamp 3a is diffused by the light guide section 4 to a direction of the liquid crystal panel 5 and is modulated in a manner to correspond to a display image on the liquid crystal panel 5 and is then emitted to the side of the display surface.
FIG. 7 is a schematic diagram illustrating configurations of another conventional liquid crystal display disclosed in the above patent reference. The liquid crystal display, as shown in FIG. 7, includes an image receiving section 11, a judging section 12, a sorting section 13, a switching section 14, and a display device 15. The display device 15 has a peripheral portion driving section 15a, a central portion driving section 15b, and a moving image corresponding control section 15c. The display surface (screen) of the display device 15, as shown in FIG. 8, has a display element section 16 making up its central portion and a display element section 17 making up its peripheral portion. An exclusive backlight (not shown) is formed on the display element section 16.
In the above liquid crystal display, image data output from the image receiving section 11 is sorted into two groups in the sorting section 13, one group being displayed in a peripheral portion of the display screen and another group being displayed in a central portion of the display screen and the image data to be displayed in the peripheral portion is transmitted via the switching section 14 to the peripheral portion driving section 15a of the display device 15 and the image data to be displayed in the central portion is transmitted via the switching section 14 to the central portion driving section 15b of the display device 15. Moreover, a judgement of whether the above image data is to be corresponded to a moving image or to a static image is made by the judging section 12 and, if the image data is to be corresponded to a moving image, the image data being displayed in the central portion having been sent out from the sorting section 13 is transmitted via the switching section 14 to the moving image corresponding control section 15c in the display device 15. The moving image corresponding control section 15c lets the sent-out image data be displayed on the display element section 16 making up the central portion on the display surface and turns on a backlight (not shown).
However, the conventional liquid crystal display devices described above have following problems. That is, in the liquid crystal display device shown in FIG. 6, when a moving image is to be displayed, the lamps 3a and 3b alternately flash during one frame and, at this point, while the lamps 3a and 3b are being lit, in the liquid crystal panel 5, liquid crystal cells whose responding operations to pixel data have been completed and liquid crystal cells whose responding operations to pixel data have not been completed exist, thus causing occurrence of a luminance inclination in the display screen. The brightness inclination becomes conspicuous as the liquid crystal panel 5 becomes large in size, which presents a problem in that a quality of a displayed image declines.
Moreover, the liquid crystal display device shown in FIG. 7 is fabricated on the premise that a moving image is displayed only in a center portion of the display screen and, therefore, lighting of the backlight (not shown) is performed in a manner to correspond to a static image in a peripheral portion of the display screen and, when a moving image is to be displayed in the peripheral portion of the display screen, an afterimage occurs, which presents a problem that a quality of the displayed image declines.